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A small change in word strength

If you've been using Duolingo for a few months, you might notice that some of your strength bars shifted up/down a bit today. That's because we made some adjustments to the word strength predictor.

This is a minor change, so most of you might not notice anything. But it fixes a bug that caused the words you know really well to stay at four bars (and unavailable for practice) for a long time... and then suddenly drop to one bar after a few months! Now everything degrades gradually like it should.

September 27, 2013



can you also consider changing word strengh for new words learned?

it shouldn't be maximum! when I learn a new word i wanna practice it again so it will stick into my head. its easy to forget a full lesson


Words are bumped to 4 bars whenever you learn or practice them, but the decay rate depends on how often you get them right or wrong (so new words decay in a day or two, words you've gotten right 10+ times might take months). We're always tweaking things under the hood, and hope to have this perfected soon. :)


Its been my experience that it doesn't always work this way. I wish I had a better example, but as I stated below, I have been going through my vocab list to practice words I hadn't seen in a while. The best current example I have is fecha which I have seen 6 times, last seen a month ago still with full bars. The last time I saw this word was during the initial introduction of it (which knowing me, probably took more than one time to complete the lesson).


Consider, please, that the first learning of word goes to 2 or 3 bars (a middle strength). Then succeeding correct answers build it up to 3 or 4 bars. A word at 4 bars really would then demonstrate a series of correct answers. And thus the decay rate may even be less for a 4 bar word (that earned that status) as opposed to a lower-bar word.


grazie per la tua risposta!

i was also thinking maybe one day users will be able to choose decay levels for the words they wanna practice more by themselves..


The end effect for new words is not like that though. Maybe the different exercise types skew it, since it is almost trivial to get spoken (say or type) and multiple choice questions (both textual and pictoral) right. Adding translating from that word and, what, that's more than half the exercise types and the word strength can easily be overblown.


I agree. After I see a word once I don't automatically remember it for even a short period of time. I need to see it again and again for it to stick.


Though many of us do need to see a word repeatedly before it sticks, I see some benefits to duolingo's methods. For starters, it makes my mind work harder. My mind doesn't have to work very hard when recalling a word if I have repeatedly exposed it to that word. With this method that duolingo uses, it rewards those who get very good at imprinting a word into their mind upon a single view.

I know it may seem counterintuitive at first, but I do believe duolingo's spaced repetition algorithms are much more beneficial than many realize. Just think about how much more quickly we could learn a language (or anything else for that matter) if we could all get better at having a word or concept lodge solidly in our brains upon just one viewing of it?

Those with photographic memories already do this I imagine, but I, and many others weren't born with a photographic memory. Are we able to make our minds become more photographic? I suspect that we can, and duolingo just might be one of the tools we can use to take our minds to a higher level.

For any of you interested in reading more about photographic memory (also known as eidetic memory), you can start with this:

Eidetic memory

If you really love repetition, then you may never be interested in seeing the benefits of another method, but duolingo's methods may be more beneficial than meets the eye.


Repetition in context is more effective and useful than mere repetition of the word as with flashcards or something similar. WHY?

The basic brain patterns of the two memories are different. The latter are isolated memories, and it takes more steps and time to access them when needed, either in recognition and understanding input or speaking/writing as output. A simple case of this is a basic structure of a language, .e. g, »he is« or »she has,« Memorizing the conjugation of »is» or »has« puts the info in a kind of vertical arrangement. But actual use of this information is parallel and it takes extra time and steps to convert the stored firmly embedded information before it can be used. Of course once the person repeatedly uses the information, either as understanding input or creating output by speaking or writing, the parallel paths become firmly imbedding into fast accesssable paths. But way not develop the brain pathways in directly usable form from the start?

You see this in the development of fluency when language is learned by studying grammar, memorizing vocabulary and translation practice. Fluency is achieved not from this study but only after extensive immersion in the language.

For those interested in this further I I can email a paper that I wrote a while ago on the topic to anyone who requestes it. (weiher@udel.edu) I often do not follow the internal communication systems in Duolingo so a direct emai to me is preferable for such a request.

Conclusion: The best repetitions in Duolingo are those that involve full phrases, rather than those using isolated words. Repetition in context is also less boring (i.e. more interesting) and hence more useful. This suggests that the incorpoation into Duolingo of short connected stories as sets of serial type orderd exercises, each involving a full phrase, would be an excellent addition to Duolingo.

PS; The current measure of fluency used by Duolinguo really "sucks." Useful for the rank beginner, often grossly in error for more advanced. I have even observed scores of fluency less than 40% for native speakers of German and other's that are much more fluent than that. For rank beginners it can be motivating but for advanced uses demotivating. NUFF SAID.


I assume that word strength decays more quickly on new words, but, as I said in my other comment, it's difficult to tell, at present, how their algorithm works.


Though minor, that certainly doesn't mean it won't be appreciated! Every little improvement is a help! Thanks for the fix! :)


This is great news! Thanks again, Tatou!


In other SRS programs I've used, such as Anki, the sorting algorithm is a bit more transparent. That is: the user can clearly see when individual facts will become due again. This might decrease complaints about word strength, or, at least, direct them in a more constructive direction.


There is definitely a huge improvement. I could "Practice Weakest Words" over and over again, and my tree would never return to gold. And lessons that did, would be back to blue or green again in a few days.

Today, I've been practicing weakest words off and on and if you take a look, my tree is almost completely golden again!


I noticed this improvement last night - finally I'm seeing words i haven't seen for ages like marmellata - I didn't remember them and practicing has suddenly become difficult again!


I seem to be seeing the same words over and over again in practice. Again, thanks for the minor change :D I have noticed some words that I haven't seen for weeks, but when I go into vocabulary and click the "last practiced", it shows me words from a month ago with full bars, yet words that I practiced yesterday and almost everyday, have 2 bars.


It sounds like you're experiencing the problem described in this thread: http://www.duolingo.com/comment/862708 . Hopefully this problem will get resolved soon.


Do you think it would hurt the learning experience for users to self-identify words they feel they need to practice more often? For example, I often feel that way about certain words that come up in the lessons. Even if I get them right occasionally, I want more practice. Would be great if Duolingo offered a "more practice" option when you hover over a word in a lesson. That option would let Duolingo know you want more practice in that word.


Yes! Maybe then I won't need my custom Memrise list


Studying Spanish currently, I still find this word strength needs to be tweaked more. Now it's too easy to increase the skill level of a word. I'd say that only typing the translation, both ways can increase the strength to the maximum. All the other exercises can rely too heavily on other skills or tricks. E.g. if you know the other option(s) are not valid the one remaining must be. Also in the type of question where all the words are given, the first word should NOT have a capital, because this will let you know what the first word must be. A very easy improvement is to remove all capitals always in those type of questions. Also I'd like to be able to specify myself what words I'd like to train more (from the Words menu) e.g. a tick box at each word "I need more training" .

But I still love Duolingo and will keep using it. Big thanks to all who made this possible. :-)


Thank you now i dont have to strengh my words each week!


Thank you for the head's up. I haven't seen any change in my own word strength which is a bit of a surprise because usually I can tell when you guys have been mucking around with word strength.


A question: Does the word strength predictor also pick up on immersion/translation work, or is it limited to the lesson trees?



Yes, when you translate a sentences with a word in your vocabulary from immersion/real-world practice, it will get refreshed!


That is perfect. Thank you. More incentive to get back to translations then.


Getting credit for work done in immersion is a really smart feature for this program and I'm glad the developers included it.

I have a follow-on question, however. If, during immersion, a word in a locked lesson is translated, and translated correctly, will that lesson then unlock/open up/become available?


Thanks for all your work!
I noticed I have words I haven't seen in a month showing up with full bars, but your overall decay rates may just be slower than I would like. I just 'fix' this issue myself by sorting words by last practiced and redoing individual sections that contain words I haven't seen in over a month. This also seems to have improved my weakest words section because I am bound to make a mistake or two, and the words I miss will show back up for practice... sometimes.


what if i l look at the translation of the word (hover over the word) and get it right afterwards? Is it counted as "correct"? I think this shouldn't be counted as correct because i did not remember the word, I just knew it after looking at it...


According to posts by Luis in other discussions, it's counted as correct with respect to refreshing the word's strength, but peeking causes that word's strength to decay more quickly. Based on other posts by Luis and Tatou, this is similar to what happens when you get a word wrong, but the changes to decay rates might be different.


pinkodoug is correct, although we are always running experiments to see what works best. we'll make announcements when anything changes.

[deactivated user]

    Interesting. I had no idea that peaking affects your word strength.

    [deactivated user]

      And well what do you do when a word is presented for the first time, and you really have to peak to learn it? I would think that's the time when most people would peak. So it's not necessarily only because you forgot a word.


      The first time you're presented with a word, it's flagged as a new word, and it's highlighted to show this. As far as I know, there's no penalty for peeking when a word is shown to a user for the first time. In another thread, Luis indicated that not peeking at a word, which might indicate that you're already familiar with it, will actually cause that word's strength decay rate go down.

      [deactivated user]

        I see now. Thank you for the clarification!


        Can you help me understand how the word "gelato" in Italian lost bars? I knew this word even before I started learning Italian with Duolingo. I have low bars on other words that I know very well and have strong bars on the words that I forgot. Another question. If I want to strengthen my bars and practice this particular word what should I do and how to get to the lesson that is using this particular word? There are so many lessons. I am confused. Thank you for your help.


        I have the problem where a word that I keep practising over and over again won't go back to its full strength.

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